import re

mystr = """<ul class="islider-outer"><li class="islider-html islider-prev" style="transform: translateZ(0px) translateX(-375px); overflow: auto; visibility: visible; transition: none 0s ease 0s;"><img src="//t00img.yangkeduo.com/goods/images/2018-09-13/03fab2ade51542225d661b9cb45efb9d.jpeg" "="" data-url=""></li><li class="islider-html islider-active" style="transform: translateZ(0px) translateX(0px); overflow: auto; visibility: visible; transition: -webkit-transform 227.2ms ease 0s;"><img src="//t00img.yangkeduo.com/goods/images/2019-06-03/408229ef-1f9c-4bcc-b764-3f30f7deb6d6.png" "="" data-url=""></li><li class="islider-html islider-next" style="transform: translateZ(0px) translateX(375px); overflow: auto; visibility: visible; transition: -webkit-transform 227.2ms ease 0s;"><img src="//t00img.yangkeduo.com/goods/images/2019-06-03/644f5a2f-c928-4955-ada6-89f2f0f1ff3f.jpg" "="" data-url=""></li></ul>"""

restr = r'<ul class="islider-outer">.*?src=\"(.*?)\".*?src=\"(.*?)\".*?src=\"(.*?)\".*?</ul>'

cc=r"<[img]{3}\ssrc=\"(.*?)\""


regex = re.compile(restr, re.I)
mylist = regex.findall(mystr)
print(mylist)
